Control of the level of the signal produced by a transceiver coupled to a power distribution line

Abstract

A method for controlling the level of a signal produced by a transceiver of digital data coupled to a power distribution line during a transmission phase is provided. The level of the signal output by the transceiver is regulated by comparing the current level of the output signal with a predetermined minimum threshold and a predetermined maximum threshold, reducing the current level when the maximum threshold is exceeded by reducing the gain, and switching to a voltage mode control of the output signal when the current level of the output signal becomes lower than the minimum threshold.

That which is claimed is:  
     
       1. A method of regulating an output signal level for a transmitter connected to a power distribution line, the method comprising: 
       comparing a current of the output signal with a minimum current threshold and a maximum current threshold;  
       reducing the current of the output signal when the maximum threshold is exceeded; and  
       switching to a voltage control mode for controlling the output signal when the current of the output signal is lower than the minimum threshold.  
     
     
       2. The method of  claim 1 , wherein reducing the current comprises reducing a gain of the output signal. 
     
     
       3. The method of  claim 1  wherein switching to the voltage control mode further comprises comparing a voltage of the output signal with a low voltage threshold and a high voltage threshold and regulating a gain of the output signal to maintain the voltage within the low and high voltage thresholds. 
     
     
       4. The method of  claim 3  wherein the low voltage threshold is less than about 1 V. 
     
     
       5. The method of  claim 3  wherein the high voltage threshold is greater than about 2 V. 
     
     
       6. The method of  claim 1  wherein the minimum current threshold is less than about 200 mA. 
     
     
       7. The method of  claim 1  wherein the maximum current threshold is greater than about 400 mA. 
     
     
       8. A method of regulating an output signal level for a transceiver of digital information connected to a power distribution line during a transmission phase, the method comprising: 
       comparing a current of the output signal with a minimum current threshold and a maximum current threshold;  
       reducing the current of the output signal when the maximum threshold is exceeded by reducing a gain of the output signal; and  
       switching to a voltage control mode for controlling the output signal when the current of the output signal is lower than the minimum threshold.  
     
     
       9. The method of  claim 8  wherein switching to the voltage control mode comprises comparing a voltage of the output signal with a low voltage threshold and a high voltage threshold and regulating the gain to maintain the voltage within the low and high voltage thresholds. 
     
     
       10. The method of  claim 9  wherein the low voltage threshold is less than about 1 V. 
     
     
       11. The method of  claim 9  wherein the high voltage threshold is greater than about 2 V. 
     
     
       12. The method of  claim 8  wherein the minimum current threshold is less than about 200 mA. 
     
     
       13. The method of  claim 8  wherein the maximum current threshold is greater than about 400 mA. 
     
     
       14. A device for regulating an output signal level for a transmitter connected to a power distribution line, the device comprising: 
       a voltage amplifier receiving the signal and having a gain controlled by a control signal;  
       a current amplifier coupled to an output of said voltage amplifier and delivering the signal to the transmission line;  
       a current sensor connected to an output of said current amplifier;  
       at least one first comparator for comparing a voltage on the current sensor with first predetermined high and low thresholds and providing first and second logic signals; and  
       at least one second comparator for comparing a signal corresponding to an output voltage of said current amplifier with second predetermined high and low thresholds and providing third and fourth logic signals; and  
       a control logic circuit receiving the first, second, third, and fourth logic signals and outputting the control signal.  
     
     
       15. The device of  claim 14  wherein the first signal has first and second logic values associated therewith; and wherein the control signal is set to reduce the gain if the first signal assumes the first logic value. 
     
     
       16. The device of  claim 14  wherein the first and second logic signals each have first and second logic values associated therewith; and wherein the control signal is set to maintain the gain if the first and second logic signals assume the second logic value. 
     
     
       17. The device of  claim 14  wherein the current sensor comprises a current sensing resistor. 
     
     
       18. The device of  claim 14  wherein the current sensor comprises a current mirror. 
     
     
       19. The device of  claim 14  wherein said current sensor is connected in series to the output of said current amplifier. 
     
     
       20. The device of  claim 14  wherein the at least one first comparator comprises a pair of comparators; and wherein one of said pair of comparators compares the voltage on the current sensor with the first predetermined high threshold and provides the first logic signal; and wherein the other of said pair of comparators compares the voltage on the current sensor with the first predetermined low threshold and provides the second logic signal. 
     
     
       21. The device of  claim 14  wherein the at least one second comparator comprises a pair of comparators; and wherein one of said pair of comparators compares the signal corresponding to the output voltage with the second predetermined high threshold and provides the third logic signal; and wherein the other of said pair of comparators compares the signal corresponding to the output voltage with the second predetermined low threshold and provides the fourth logic signal. 
     
     
       22. The device of  claim 14  wherein the first, second, third, and fourth control signals have first and second logic values associated therewith; and wherein the control signal is set to increase the gain when the second and fourth signals assume the first logic value; wherein the control signal is set to decrease the gain when the second and third signals assume the first logic value; and wherein the control signal is set to maintain the gain when the second signal assumes the first logic value and the third and fourth signals assume the second logic value. 
     
     
       23. A device for regulating an output level for a transmitter connected to a power distribution line, the device comprising: 
       at least one comparator for comparing a current of the output signal with a minimum current threshold and a maximum current threshold;  
       a circuit for reducing the current of the output signal when the maximum threshold is exceeded; and  
       a controller for switching the device to a voltage control mode for controlling the output signal when the current of the output signal is lower than the minimum threshold.  
     
     
       24. The device of  claim 23  wherein the circuit reduces the current by reducing a gain of the output signal. 
     
     
       25. The device of  claim 23  wherein the minimum current threshold is lower than about 200 mA. 
     
     
       26. The device of  claim 23  wherein the maximum current threshold is greater than about 400 mA. 
     
     
       27. A coupling interface for a transceiver of digital information coupled to a power distribution line for regulating the level of a signal to be transmitted on the power distribution line during a transmission phase, the coupling interface comprising: 
       a voltage amplifier receiving the signal and having a gain controlled by a digital control signal;  
       a current amplifier coupled to an output of said voltage amplifier and delivering the signal to be transmitted to the power distribution line;  
       a current sensor connected in series to an output of said current amplifier;  
       a first pair of comparators for comparing a voltage on the current sensor with a first pair of predetermined high and low thresholds and providing a first pair of first and second logic signals;  
       a second pair of comparators for comparing a signal corresponding to an output voltage of said current amplifier with a second pair of predetermined high and low thresholds and providing a second pair of third and fourth logic signals; and  
       a control logic circuit receiving the first and second pairs of logic signals and outputting the digital control signal.  
     
     
       28. The coupling interface according to  claim 27  wherein the first signal has first and second logic values associated therewith; and wherein the digital control signal is set to reduce the gain if the first signal assumes the first logic value. 
     
     
       29. The coupling interface according to  claim 27  wherein the first and second logic signals each have first and second logic values associated therewith; and wherein the digital control signal is set to maintain the gain if the first and second logic signals assume the second logic value. 
     
     
       30. The device of  claim 27  wherein the current sensor comprises a current sensing resistor. 
     
     
       31. The device of  claim 27  wherein the current sensor comprises a current mirror. 
     
     
       32. The coupling interface according to  claim 27  wherein the first, second, third, and fourth control signals have first and second logic values associated therewith; and wherein the digital control signal is set to increase the gain when the second and fourth signals assume the first logic value; wherein the digital control signal is set to decrease the gain when the second and third signals assume the first logic value; and wherein the digital control signal is set to maintain the gain when the second signal assumes the first logic value and the third and fourth signals assume the second logic value.